Differential Diagnosis for Psoriasis
- Single most likely diagnosis
- Psoriasis: The clinical presentation of well-demarcated, erythematous, scaly plaques, particularly on the elbows, knees, scalp, and lower back, is highly suggestive of psoriasis. The presence of Auspitz's sign (bleeding points after scale removal) further supports this diagnosis.
- Other Likely diagnoses
- Seborrheic dermatitis: This condition can present with erythematous, scaly patches, particularly on the scalp, face, and torso. However, the distribution and morphology can help differentiate it from psoriasis.
- Atopic dermatitis (eczema): Characterized by pruritic, erythematous, and scaly lesions, often in a different distribution than psoriasis, such as the flexural areas.
- Pityriasis rubra pilaris: A rare skin disorder that can mimic psoriasis, characterized by small, pointed bumps on the skin and reddish-orange patches.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Cutaneous T-cell lymphoma (Mycosis fungoides): Although rare, this condition can present with skin lesions that resemble psoriasis. Missing this diagnosis could lead to delayed treatment and poor outcomes.
- Sarcoidosis: This systemic disease can cause skin lesions that may mimic psoriasis, and missing the diagnosis could lead to untreated systemic involvement.
- Rare diagnoses
- Pityriasis lichenoides: A rare skin condition characterized by small, scaling papules that can resemble psoriasis.
- Dermatomyositis: An inflammatory disease characterized by skin and muscle involvement, which can present with skin lesions similar to psoriasis.
- Lichen planus: A chronic inflammatory condition that can affect the skin, mucous membranes, and other areas, sometimes presenting with lesions that could be confused with psoriasis.